Grinding machine



July 1, 1958 c. M. GRINAGE GRINDING MACHINE I 12 Sheet-Sheet 1 Filed Dec. 5, 1952 mom INVENTOR- CLAUDE M. GRINAGE July 1, 1958 c. M. GRINAGE GRINDING mcnmz l2 Sheets-Sheet 2 Filed D00. 5. 1952 f INVENTOR. CLAUDE GRINAGE July 1, 1958 c. M. GRINAGE 2,840,955

GRINDING MACHINE Filed Dec. 5, 1952 12 Sheets-Sheet 3 m o D:

n T f E h D N o INVENTOR.

CLAUDE M. GRINAGE July 1, 1958 c. M. GRINAGE GRINDING MACHINE 12 Sheets-Sheet 4 Rm w [III/11111111111111),

. Filed Dec. 5, 1952 INVENTOR. CLAUDE M. GRINAGE FIG. 5

July 1, 1958 c. M. GRINAGE GRINDING MACHINE Filed Dec. 5, 1952 12 Sheets-Sheet 5 FIG] (MANUAL POSITION) ,INVENTOR, CLAUDE M. GR l NAGE Q z W July 1, 1958 c. M. GRINAGE GRINDING MACHINE 12 Sheets-Sheet 6 Filed Dec. 5, 1952 INVENTOR. CLAUDE M. GRINAGE July 1, 1958 c. M. GRINAGE 2,840,956

" GRINDING MACHINE Filed Dec. 5, 1952 12 Sheets-Sheet 7 FIG.9 (FINE FEED um I as INVENTOR. H CLAUDE M. GRINAGE BY FIG. l0 (FINE FEED uowm y 1, 1958v c M. GRINAGE 2,840,956

GRINDING MACHINE FiledDec. 5, 1952 12 Sheets-Sheet a FFD PCS FIG. ll (FEED um INVENTOR CLAUDE M. GRINAGE 8 FIG. l2 (FEED DOWN) y 1, 9 c. M. GRINAGE 2,840,956

GRINDING MACHINE INVENTOR. CLAUDE M. GRINAGE July 1, 1958 c. M. GRINAGE GRINDING MACHINE l2 Sheets-Sheet 11 Filed Dec. 5, 1952 CONTROL m m EM F V IA H T 6 DS w E B M mm m mm F m D C 8 T C M m P m 0 F m G R 6 s 1 E M RR m um F m D R Q A @USB F|GI4) (IOGE FIGJZHQ FINE FEED DRIVE STOP DRIVE J06 (I041 FIG. l3)

FINE FEED SELECTOR (I78 30C FIG. 14)

STOP

(IG FIG. l4)

MOTOR GEN. MOTOR GEN.

START "a 2E FIG. [4) TRAVERSE MOTOR 200 ON OFF MAGNETIC CHUCK INVENTOR. (lol H313) CLAUDE M. GRINAGE FIG. l6

United States Patent 2,840,956 GRTNDING MACHINE Claude M. Grinage; Stratford, Conn., assignor to The Ballard Company, a corporation of Connecticut Application December 5, 1952, Serial No. 324,348 40 Claims. or. 51-50) The present invention relates to machine tools and particularly to a new and improved vertical grinding machine.

The principal object of this invention isto provide an extremely versatile grinding machine that can be pie-set for a predetermined cycle of operations from either of two convenient locations relatively to the machine.

Other objects of the invention include the provision of a grinding machine and a control circuit therefor that will permit automatic grinding to within one ten-thousandths of an inch from a shoulder on a work piece withoiit damaging the latter; the provision of such a grinding machine and control circuit therefor that will enable accurate repetitive reciprocative grinding strokes to within one ten-thousandths of an inch; the provision of such a griding machine and a grinding wheel dresser 80 associated with the grinding machine that the grinding wheels dressed thereby have a work surface in exact parallelism with the ways of the grinding headpthe provision of such a grinding machine and a pre-settable automatic cycle controller therefor in combination with a grinding wheel dresser, arranged so that at any point during the cycle of operation, the grinding wheel can be raised to its upper position and dressed with subsequent continuation of the cycle without in any way disturbing the pre-set cycle of operations; the provision of such a grinding machine and control circuit therefor having dual control stations that are interlocked in such a manner that when one set of controls is effective, the

other is ineffective; the provision of such a grinding machine in which a combined mechanical and hydraulic actuating means is employed, embodying dual purpo se elements; the provision of such a grinding machine and control therefor in which the grinding head can be controlled manually, either mechanically or hydraulically,

and automatically controlled hydraulically; the provision of such a grinding machine having an electrical control circuit that can be pre-set to produce different automatic cycles of operations of the grinding mechanism including machine including a main grinding head and a side grindving head, both having the features heretofore enumerated. The above, other objects and novel features of the invention will become apparent upon a consideration of the following specification considered in connection with the accompanying drawings, in which:

Figure 1 is a front elevational view of a vertical grinding machine to which the principles of theinven- :tion have been applied;

Fig. 2 is a right side elevational view of the grinding machine shown in Fig. 1;

2,840,956 Patented July 1, 19 58 Fig. 3 is a top plan view of the grinding machine shown in Figs. 1 and 2;

Fig. 4 is a partial sectional elevational view taken substantially along line 4--4 of Fig. l; p

Fig. Sis a sectional elevational view taken substantially along line 5-5 of Fig. 4; I

Fig. 6 is a sectional plan view taken substantially along line 6-6 of Fig. 4; v

Figs. 7 to 12, inclusive, are diagrammatic views of certain portions of the apparatus in various conditions to produce certain operations of one of the grinding heads;

Figs. 13, 14 and 15 are wiring diagrams for controlling the various cycles of operation of the grinding machine;

Fig. 16 is a top plan view of the left-hand control station shown in Fig. 1;

Fig. 17 is a top plan view of the right-hand control station shown in Fig. 3; and

Fig. 18 is a sectional view of one of the cam switches of the control.

Referring to the drawings and particularly to Figs. 1, 2 and 3, the principles of the invention are shown as applied to a vertical type of grinding machine including a standard S to the bottom of which is integrally attached a base B. A work-supporting table W is rotatably mounted on the base B in spindle bearings not disclosed.

The principles of the invention are applied to a machine of the type similar to that shown, described and claimed in Patent No. 2,355,625, in the name of Edward P. Bullard, III, to which patent reference is made for details of similarity between the two structures which are not specifically described herein.

A cross-rail C is mounted on bearings located on the front fact of the standard S and it supports a main grinding head H The rail C is adapted to be moved vertically along the bearings on the front face of the standard S, while the grinding head H is adapted to be moved horizontally along bearing ways on the crossrail C. The horizontal movement of the grinding head H is effected by a feedworks transmission F located on the right-hand side of the cross-rail C. H

A side head H is mounted on one front corner and side of the standard S and it is adapted to be moved vertically by an additional feedworks transmission F A grinding head H is mounted on the side head H in somewhat the same manner as the grinding head H is mounted on the cross-rail C. The grinding head H is adapted to be moved vertically with the side head H through the action of the feedworks F Referring to Fig. 2, a headstock transmission T is mounted within the bottom of the standard S and is operatively connected to a variable-speed drive VS (Fig. 3) located on the outside of the machine. The headstock transmission T is of any fixed-ratio type, having change gears to vary the speedratio produced by it. Thetransmission per se forms no part of the invention, and, therefore, a specific description thereof is believed unnecessary.

The two feedworks F and F are standardized so that identical constructions are employed, permitting interchangeability of the two. The headstock transmission T (Fig. 2) supplies power for both the feedworks F and F in the same manner that the headstock T of Patent 2,355,625 supplies the power for all of the feedworks transmissions of that patent.

Each of the grinding heads H and H includes a builtin electric motor for rotating its grinding wheel. These grinding wheels are adapted to be reciprocated along the longitudinal axes of the heads H and H by an electrically-controlled hydraulic circuit adapted to be pre-set to provide various cyclic operations of the grinding wheels.

Control stations LCS and i-lCS are located on the left and right sides of the machine, respectively (Fig. 3). The LCS station includes electrical control switches and apparatus for controlling the operation of the main grinding head H and the RCS station includes controls for the main head H and controls for the side grinding head H Work is adapted to be magnetically held on the work table W and rotated at a predetermined speed depending upon the change gears in the headstock transmission T and the setting of the variable-speed drive VS. The grinding heads H and H are adapted to be moved into work-operating position by the feedworks F and F at which location they are adapted to be rotated and reciprocated, the latter hydraulically in accordance with a predetermined cycle to effect the desired grinding operation on the work attached to the table W.

Referring to Figs. 1, 2 and 3, the standard S comprises a substantially hollow, vertically-disposed housing 20, provided with bearing supports for the transmission T; and the base B comprises a substantially cylindrical shell 21, integral with the lower end of the standard S.

The work-supporting table W is shown as a magnetic chuck, and includes a vertically-disposed spindle (not shown) that is mounted in suitable bearings Within the base B somewhat in the manner shown in Patent 2,355,625.

Referring to Fig. 2, an output gear 22 of the transmission T meshes with a beveled ring gear 23 fixed to the under surface of the work-supporting table W. The headstock transmission T, as previously explained, comprises a fixed-ratio transmission including pull gears 24 and 25 that are supplied with power through a pinion 26 integral with a drive shaft 27 that extends rearwardly to the outside of the housing 20. The outer end of shaft 27 has keyed to it a V-groove pulley 28 in driving engagement with a similar V-groove pulley attached to a direct current motor 29 forming part of the variable-speed drive VS (Fig. 3). The VS drive includes a generator 30 that operates on alternating current and supplies direct current to motor 29. A control panel 31 is provided for varying the speed of the motor 29 in a well known manner. The cross-rail C is of the same construction as that disclosed in Patent 2,355,625, and is adapted to be moved vertically along the ways 32 and 33 on the front face of the standard S in a somewhat similar manner as the crossrail C is moved along the standard of the above-referredto patent.

Referring to Fig. 4, a saddle 34 is attached to the cross-rail C for movement horizontally along ways 35 and 36 on the rail C. A nut 37 is rigidly attached to the back face of the saddle 34 and threadingly receives a screw 38 (Figs. 1 and that is adapted to be rotated at varying speeds by the feedworks F in the same manner that the screw 218 is rotated by the feedworks F of the amove-referred-to patent.

The feedworks transmissions F and F are similar to the feedworks transmissions of Patent 2,355,625, except that those of the patent are designed to move the main head and side head vertically and horizontally, whereas the feedworks transmissions F and F of the present embodiment of the invention are adapted to move the main head horizontally and the side head vertically. This is accomplished by eliminating from the feedworks transmissions those parts which were required to effect the vertical motion of the main head and the horizontal motion of the side head. The elimination of these parts in no way affects the operation of these feedworks transmissions With respect to the desired motions of the head, but reduces the cost of manufacture thereof by approximately one-half. The similarity between the structure of the present invention and that of the above-referred-to patent does not extend to the source of power for the 4 traverse motion of the main head H and the side head H, since, in the present case, this relatively rapid traverse rate of operation of the feedworks F and F is provided by a shaft 39 that is supplied with power from an electric motor 40 (Fig. 3). Furthermore, although the gear-shifting elements in the feedworks of Patent 2,355,625 are mechanically operated, those in the present invention are hydraulically actuated under solenoid control, as will be explained later.

Referring to Fig. 4, the main grinding head H includes a housing member 41 having a recess for receiving a pilot 42 that is integral with the saddle 34. The T-heads of bolts 43 are adapted to ride within arcuate T-slots 44 formed on the front face of the saddle 34. Nuts 43' are employed to lock the housing 41 to the saddle 34. The construction and arrangement of the parts provide a swivel action of the main grinding head H about the center-line of the pilot 42. A worm wheel 45 mounted on the back of the head H, meshes with an arcuate rack 46 on the saddle 34, and the former includes wrenchengaging ends 47 (Fig. 1) for effecting the swivel action of the head H manually.

The housing 41 of the main grinding head H includes within it a reciprocable carriage 48 that is adapted to ride within guide ways 49' formed on the inner back wall of the housing 41. The carriage 48 supports an alternating current motor 49 on the output spindle of which is rigidly fixed the grinding wheel 50. The carriage 48 also includes a cylinder 50' within which is located a piston 51 that is connected to a stationary rod 52 that is rigidly mounted on the top plate 53 of the grinding head housing 41. Liquid under pressure is adapted to be trans mitted through passages within the center of the rod 52 to opposite sides of the piston 51 in a manner to be described later, for effecting the vertical reciprocation of the cylinder 50'. Manual reciprocation of the carriage 48 can be effected by the rotation of a hand-wheel 54 in opposite directions. The hand-wheel 54 is in driving engagement with a beveled pinion 55 that meshes with a similar beveled pinion 56 which latter is splined to a vertically-disposed shaft 57.

Referring to Fig. 5, the splined shaft 57 has a spur gear 58 fixed to its upper end that meshes with one gear of a reduction train 59. The last gear in the train 59 is keyed to a screw shaft 60 that meshes with a worm gear 61 rotatably mounted in a housing 62 that is fixed to the main head H The worm gear 61 is adapted to be held against rotation when it is desired manually to reciprocate the carriage 48, and to this end, the threaded shaft 60 is mounted in a bracket 60' that is attached to the carriage 48 by a web 60". When the worm 61 is held against rotation, it acts as a nut so that rotation of the screw 60 effects vertical movement of the carriage 48. I

Referring to Fig. 6, the worm gear 61 is keyed to a sleeve member having positive engagement clutch teeth 63 adapted to mesh with mating clutch teeth on an axiallyshiftable, non-rotatable sleeve 64. A compression spring 65 is provided between the axially-movable sleeve 64 and the one end of a housing 66 that contains the sleeve 64. An abutment screw 67 is fixed to the axially-movable sleeve 64 and is adapted to operate an electrical switch LS for a purpose to be described later. The sleeve 64 includes an annular portion 68 forming a piston that rides within a cylindrical bore 69 of the housing 62. The construction and arrangement of the parts are such that introduction of liquid under pressure on the right-hand side of the piston 68 (Fig. 6) disengages the clutch teeth 63 and those on the sleeve 64 by axially moving the sleeve member 64 leftwardly, compressing the spring 65. With the parts in this condition, vertical reciprocation of the carriage 48 by the introduction of liquid under pressure alternatively to opposite faces of the piston 51 (Fig. 4) will cause the carriage 48 to reciprocate together with the screw 60 and in so doing, the worm gear 61 will merely idle on its rotative axis, Release of the liquid under pressure on the right-hand side of the piston 68 will cause spring 65 to force sleeve 64 rightwardly until the teeth on the right-hand end of the sleeve mesh with the teeth 63 on the sleeve which supports the worm wheel 61. In this condition, the worm gear 61 cannot rotate, and acts as a nut causing, upon rotation of screw 60, vertical movement of the carriage 48.

Previously, it was described how the main grinding head H was moved horizontally along the ways of the carrier by the action of the feedworks F Manual movement of the head H horizontally along the crossrail C is effected by the rotation of either hand-wheels 70 or 71 (Fig. 1). The hand-wheel 70 functions similarly to the hand-wheel 413 of Patent 2,355,625, while the hand-wheel. 71 is adapted to effect rotation of the screw 38 through a set of beveled pinions (not shown) between it and screw 38.

Referring to Fig. 1, the side head grinding head H is substantially identical with the main head H and is provided with a swivel mounting on the saddle of the side head H in substantially the same way that the swivel mounting 45, 46 is provided on the saddle 34. The grinding head H is also provided with an arcuate rack 72 that cooperates with a worm 73 on a shaft '74 having a wrench engaging end portion. Inasmuch as the construction of a horizontally reciprocable grinding head is substantially identical with that of the main head H further detailed description of the grinding head H is believed to be unnecessary.

Referring to Figs. 13, 14 and 15, in-line wiring diagrams are disclosed. The numerals and letters in parentheses within the text and on Figs. 16 and 17 refer to horizontal and vertical ordinates of Figs. 13, 14 and for convenience in locating the various electrical elements shown therein. The large circles represent coils of relays and will be referred to as relays. The short spaced parallel lines represent normally open switches, while the short spaced parallel lines with a diagonal line therethrough represent normally closed switches. All switches bearing the same designation as a relay coil are operated by that coil. Thus, energization of (31.3 relay (45, A) causes normally open CR3 switch (5, F) to close and normally closed CR3 switch (6, F) to open. Deenergization of CR3 relay (45, A) causes CR3 switch (5, F) to open and CR3 switch (6, F) to close.

Closing manually-operable switch 200 (101, A, Figs. 3, 13 and 16) energizes. MC magnetic chuck (101, D), as well as the CR7 relay (102, H). Energization of the CR7 relay (102, H) closes the normally open CR7 switch (106, D). Manually closing motor generator start switch (3, l-I-Figs. 14 and 16) energizes N relay (3, C) which latter closes N switches (109, CFig. 13). Closing the N switches energizes R rectifier (107, R) causing direct current to be supplied to the F field winding (102, R) of DCM motor (102, S) through adjustable rheostats 75 and 76, depending on which of the CR3 switches (104, 106, O) is closed. The DCM motor (102, S) drives the spindle of the work-supporting table W of the grinding machine. Energization of F field winding (102, R) also energizes the FL relay (106, R) which latter closes FL switch (104, A). Closing N switches (199, C) also energizes an alternating current motor ACM (112, B) which mechanically drives DCG direct current generator (102, P). Current from DCG generator does not flow to DCM motor (102, 8) until switch M (100, Q) is closed.

Preparatory to starting the machine, and referring to Figs. 16 and 13, the two cam switch stops (46, F and 58, F) are manually closed by placing hand lever 77 (Figs. 3 and 16) into position where the pointer is in line with the stop index; the two cam switch stops (45, F and 58, D) are manually closed by placing hand lever 78 (Figs. 3 andv 17) into the position where the pointer is in line with the stop index; and cam switch stop (99, G) is manually closed by placing hand lever 79 (Figs. 3 and 1 into the position where the pointer is in line with the stop index. When this has been done, CR3 relay (45, A), CR4 relay (46, A), and C1512 relay (99, B) are energized, closing normally open CR3, CR4 and CR12 switches (106, H, I and 1). Closing DSS drive start switch (106, H) energizes RR relay (107, L), thereby closing RR switch (108, A). Accordingly, M relay (108, J) is energized, closing M switch (101, Q), whereupon DCM motor (102, S) begins to rotate. With the spindle drive motor operating, assume that it is desired to control the main grinding head H from the left control station LCS (Figs. 3 and 16), the function selector hand lever 77 on the left control station LCS is moved to the desired function, such as grind. The up and down positions of the hand lever 77 (Fig. 16) are employed primarily for set-up purposes, while the manual" position, of course, is for manually controlling the movement of the grinding head. These functions will be described later. With the hand lever 77 in the position such that the pointer is in line with grind, the cam stop switch (46, F) is opened, dc-energizing CR4 relay (46, A), causing CR4 switch (48, F) to open, thereby tie-energizing IS interlocking solenoid (48, A) which, when its armature falls, mechanically locks cam switch stop (45, F) in closed position so that subsequent operation of the hand lever 78 (Fig. 17) at the right control station RCS is ineffective.

De-energization of the CR4 relay (46, A) as previously explained, causes CR4 switches (15, A and B) to open and close, respectively. Energization of the CR3 relay (45, A) causes the closing and opening, respectively, of the CR3 switches (5 and 6, F) thereby making it possible to energize the MEG main head grinding motor (6, C) upon closing one of the start switches (5, 8, D), depending upon whether clockwise or counter-clockwise rotation of the grinding wheel is desired. It follows that closing the start switches (6, 9, D) will be ineffective since CR3 switch (6, F) is open.

Assuming that it is desired to cause the main grinding head H to coarse feed up and down, FF switch (16, B) i moved to its off position. Since the circuit is set to be operated from the left control station, the left control station switch (25, I) is closed by having moved hand lever '77 to grind position (Fig. 16). With the LS switch (25, G) in the solid line position, current flows from L3 through LS TR2 switch (23, G), FCR3 switch (14, G), FCRZ switch (14, D), the feed up solenoid FU (14, C) to line L1. Current also flows through the FCRI relay (15, C) which causes FCRl switch (33, D) to close, thereby energizing the fine feed down solenoid FFD (33, B).

Referring to Fig. 11, a schematic diagram of parts of the electrical circuit and the hydraulic circuit are shown. As explained above in connectionwith Fig. 14, the feed up solenoid FU (14, C) and the line feed down solenoid FFD (33, B) have been energized which causes the respective spool valves 80 and 81 associated'therewith to move downwardly (Fig. 11).

Referring to Fig. 14, the CR9 relay (56, A) is de-energized since hand lever 77 is in grind position. Consequently, CR9 switch (52, D) is closed. Likewise, CR10 relay (5%, A) is tie-energized for the same reason, and CRIME switch (49, F) is also closed. Accordingly, solenoid CS (52, A) is energized, causing the spool valve 82 (Fig. 11) to move downwardly. Also, since CR9 switch (49, D) and C1116 switch (49, F) are closed, the TRS relay (49, A) is energized, thereby closing TR5 switch (51, B). Accordingly, the binder solenoid BS (51, A) is energized, causing the spool valve 83 associated therewith (Fig. 11) to be moved downwardly. From an inspection of Fig. 14, it is evident that the FFU solenoid (20, C), the feed down solenoid FD (27, D) and the solenoid PCS (53, A) are de-energized and their corresponding spool valves 84, 85 and 86 are-in the upper position (Fig. 11).

With the various spool valves of Fig. 11 in the position shown, liquid under pressure from the supply 37 is pumped by the unit 88 through the line 89 past spool valve 86 to line 90, thence past spool valve 85 to line 91, line 92 to the space between the top of the piston 51 and the cylinder 50 (Fig. 8). As previously described, the piston-supporting element 53 holds piston 51 fixed in space, thereby causing the cylinder 50 and the parts attached thereto including the grinding wheel 50 to move upwardly and the liquid beneath the piston 51 within the cylinder 50' to exhaust through the lines 93, 94, past the spool valve 84, thence through line 95 to an adjustable exhaust valve 96 (Fig. 11). The amount of liquid under pressure that exhausts through the metering control valve 97 from line 91 is insignificant compared to the total volume of liquid passing through line 92, and, therefore, such leakage does not materially affect the upward movement of the grinding wheel 50. The adjustable nature of exhaust valve 96 permits varying the rate of reciprocation of the grinding wheel 50 during normal grinding, while the adjustable nature of the metering valve 97 permits varying the fine feed rate of reciprocation to be described later. Liquid under pressure also passes from the pump unit 88 through a line 98, thence past spool valves 82 and 83 through a line 99 to the space above a piston 100, forcing said piston downwardly, thereby releasing the binder mechanism, which includes a toggle joint, and is either on or off. Liquid under pressure from line 98 also passes through a line 101 to the space beneath the piston 100, however, due to the differential area of the piston 100, the downwardly exerting force is greater than that which tends to force the piston 100 upwardly. Liquid under pressure from line 98 also passes the spool valve 82 through a line 102 leading to the piston 68 within the housing 66, thereby disengaging the clutch teeth 63 so that the reciprocating action of the screw 60 and the worm wheel 61 is similar to a rack and pinion.

The upward movement of the grinding head continues until an adjustable dog 103 contacts the 103 portion of the LS switch with which it is aligned. The 103' dog is not aligned with the 103 portion of the LS switch, but is in alignment with the 103' portion thereof for a purpose to be described later. The LS1 switch may be a commercial switch of the type manufactured by National Acme Company and known as a 16D switch 200ST. When the 103 dog engages the 103 portion of the LS switch (25, GFig. 14), it moves it to its dotted line position. This causes the feed up solenoid FU (14, C) and FCR1 relay (15, C) to be de-energized. Accordingly, current now flows through LS (25, G), TR1 switch (26, G), FCR4 switch (27, G), FCR1 switch (27, F), the feed down solenoid FD (27, D) to line L1. Current also passes through the FCR2 relay (28, D). Energization of the FCR2 relay (28, D) closes the FCR2 switch (20, F), thereby energizing the fine feed up solenoid FFU (20, C).

Referring to Fig. 12, CS, BS, and PCS solenoids remain in the condition they were in in connection with the description of Fig. 11, and, therefore, piston 100 has released the binder, and teeth 63 are disengaged. As above described, however, the FFU solenoid associated with spool valve 84 and the FD solenoid associated with spool valve 85 are energized, causing their respective spool valves to be moved to a lower position. The FU solenoid and FFD solenoid associated with spool valves 80 and 81, respectively, are de-energized so that their spools are now in the upward position. With the various spool valves in the position as shown in Fig. 12 by virtue of the circuit established and just described, liquid under pressure passes from the hydraulic pump 88 through the line 89, past the spool valve 86 through the line 90, past the spool valve 80, thence through line 94 to line 93, thence into the cylinder 50' beneath the piston 51 therein, thereby causing the cylinder 50 together with the grinding wheel 50 to move downwardly. The liquid above the piston 51 passes through the line 92, thence through line 91, past the spool valve 81, thence through a line 104 to an adjustable exhaust valve 105 similar to valve 96. The

amount of hydraulic fluid which passes through the adjustable flow control or metering valve 106 from line 94 does not in any way affect the downward movement of the grinding wheel 50.

At the end of the downward stroke, the adjustable dog 103' engages the 103' portion of the LS switch (25, G-Figs. l2 and 14), thereby returning it to its solid line position whereupon the cycle of coarse or normal feed up and down is repeated, at a rate depending upon the setting of valves 96 and 105. v

In many grinding operations it is desirable repetitively to grind to a positive shoulder with extreme accuracy,in the order of one ten-thousandths of an inch. In such cases, the slowest normal reciprocative speed of movement of the grinding wheel 50 is too great to repetitively stop against a positive abutment with any degree of accuracy. In the present invention this desirable function is accomplished by providing an adjustable fine feed grinding speed that can be employed at either, neither or both ends of the reciprocative stroke of the grinding wheel 50 in combination with a dwell at the positive abutment. This has been accomplished by a combination of electrical relays and hydraulic valve mechanisms which can be better understood by a description of a specific example. Assume that it is desired to coarse feed up as before, and to have coarse feed down combined with a fine feed down, the latter for a predetermined portion of, and at the end of the down stroke. Fine feed switch FF (16, B-Figs. 14 and 16) is moved to the on (solid line) position. The line feed selector switches (17, 30, C) (Figs. 14 and 16) are moved to the down position. With LS switch (25, G) in the solid line position, the feed up solenoid FU (14, C) is energized as previously described, causing the grinding head to move upwardly at a coarse feed rate until the adjustable dog 103 trips the LS switch (25, G), moving it to its dotted line position. Such action energizes the feed down solenoid FD (27, D) as described before, causing the head to feed downwardly at a coarse rate. Simultaneously with the energization of the feed down solenoid FD (27, D), current flows from L3 through LCS switch (25, I), LS switch (25, G), TR1 switch (26, H), CR2 relay (30, E), the down contact of fine feed selector switch (30, C), switch FF (16, B), CR4 switch (15, B), to L1, thereby energizing CR2 relay (30, E). Energization of the CR2 relay closes CR2 switch (31, F), thereby energizing TR2 relay (31, E). Energization of the TR2 relay (31, E) opens TR2 switch (23, G), and closes the TR2 switch (35, C). The closing of this latter switch energizes FCR4 relay (35, B) which in turn closes FCR4 switch (34, D). Closing of this latter FCR4 switch (34, D) energizes the fine feed down solenoid FFD (33, B). Simultaneously therewith, FCR4 switches (27, 28, G) open and close, respectively. When the grinding head has moved throughout the coarse feed portion of its downward stroke, the adjustable dog 103 trips the LS switch (25, G) to the solid line position. However, the feed up solenoid FU (14, C) does not become energized because TR2 switch (23, G) is open. Of course, movement of LS to its solid line position de-energizes CR2 relay (30, F), opening CR2 switch (31, H), thereby de-energizing TR2 relay (31, F), but TR2 relay (31, F) is a time-delay relay which is set to prevent closing of TR2 switch (23, G) for a predetermined time. The closing of the FCR4 switch (28, H) simultaneously with the opening of FCR4 switch (27, H) maintains energization of the feed down solenoid FD (27, D) and the FCRZ relay (28, D) upon movement of LS switch (25, G) to a solid line position. With the FCR2 relay (28, D) energized, FCRZ switch (20, F) is closed, thereby energizing FFU solenoid (20, C). With the feed down solenoid FD (27, D) energized, the fine feed down solenoid FFD (33, B) energized, and the fine feed up solenoid FFU (20, C) energized, the grinding head feeds down at a fine feed rate during the time interval pre-set on the time delay TR2 (31, F).

Referring to Fig. 10, there is disclosed an arrangement including the various spool vaives associated with the various solenoids in the condition caused by the electrical circuit having the LS switch in its solid line position after the grinding head 50 has coarse fed downwardly and is about to fine feed downwardly.

The CS and BS solenoids are energized for the same reason as described in connection with Figs. 11 and 12, and the PCS solenoid is de-energized for the same reason as described in connection with Figs. 11 and 12. The remaining solenoids FFU, FU, FD, and FFD are in the condition just described in connection with the electrical circuit for the fine feed down operation. With the spool valves in the condition as shown in Fig. 10, liquid under pressure flows through line 89 across spool valve 86, thence through line 90 across spool valve 80, thence through line 93 to the cylinder 59', causing the grinding head 50 to move downwardly. The liquid above the piston 51 within the cylinder 50 exhausts through line 92 to line 91, thence through the adjustable metering valve 97 which is set for a predetermined rate of fine feed. The valve 97 may be of the needle throttling type in which adjustment of the needle inwardly and outwardly relatively to a cylindrical orifice adjusts the flow of oil therethrough. The pre-set time delay of the TR2 time delay relay (31, F) is such that the grinding head moves down until a positive stop 110 contacts a fixed abutment whereupon the grinding head dwells for a time interval depending upon the setting of the time delay relay TR2 (31, F). This dwell is very important to insure accurate repetitive operations since the continuous application of downward force on the head I-I while it is in dwell against stop 110 relieves the apparatus of all strain and takes up all backlash so that repetitive operations of great accuracy can be obtained. At the end of the time interval pre-set on the. time relay TR2 (31, F), the TR2 switch (23, G) closes, thereby energizing feed up solenoid FU (14, C) and FCRl relay (15, C). Energization of the FCRI relay (15, C) closes the FCRl switch (33, D), thereby maintaining the fine feed down solenoid FFD (33, B) energized. This latter condition of the circuit is such as to cause the grinding head 50 to feed upwardly at a coarse or normal rate, which occurs until the dog 103 contacts the 193 portion of the LS1 switch, thereby moving the LS1 switch (25, G) to its dotted line position when the cycle of coarse feed down combined with fined feed down which is subsequently followed by coarse feed up is repeated.

Assume that it is desired to cause the grinding wheel 51) to be fed upwardly a predetermined distance at a normal rate, followed by fine feed up for a predetermined distance after which the grinding wheel 50 is to be fed downwardly at a coarse or normal rate. Referring to Fig. 16, the hand lever '77 of the cam selector switch is moved to a position such that the index thereof is ad'- jacent the grind index. The fine feed switch FF (16, B-Figs. 14 and 16) is moved to the on position, and the fine feed selector switch (17, 30, C-Figs. 14 and 16) is moved to the up position.

Referring to Fig. 14, with the various manually operable switches set as previously described, and with the LS1 switch (25, G) in a solid line position, current flows from L3 through LCS switch (25, I), thence through LS switch (25, G), TR2 switch (23, G), thence through FCR3 switch (14, G), FCRZ switch (14, D), FU solenoid (14, C), thence to L1. 'Energization of the PU solenoid (14, C) also causes energization of the FCRI relay (15, C), thereby closing FCRI switch (33, D), whereupon FFD solenoid (33, B) is energized. Referring to Fig. 11, the condition of the solenoids and spool valves is such as to cause the grinding wheel 50 to be fed up in the manner previously described in connection with Fig. 11. Simultaneously, with the energization of the PU solenoid (14, C) and the FFD solenoid (33, B), current also passes through the LS1 switch to the CR1 relay (17, F), thence through the up contact of the fine feed selector switch (17, C}, thence through the CR4 switch (15, B) to L1. Energization of the CR1 relay causes CR1 switch (18, G) to close, whereupon the TR1 relay (18, F) is energized by current passing from L3 through LCS switch (25, I), thence through CR1 switch (18, G), TR1 relay (18, F), thence through the up contact of the fine feed selector switch (17, C), thence through the CR4 switch (15, B), thence to line L1. Energization of the TRl relay (18, F) causes TRl switch (26, G) to open and TRI switch (22, F) to close. Closing of the TR1 switch (22, F) energizes the FCR3 relay (22, E), thereby opening and closing the FCR3 switches (14, G and 15, G), respectively.

As previously explained, the grinding wheel 50 is feeding upwardly at a coarse rate until the 103 dog engages the 103 portion of the LS1 switch, thereby moving it to its dotted line position. Even upon movement of the LS1 switch (25, G) to its dotted line position, the PU solenoid (14, C) remains energized through FCR3 switch (15, G) and at the same time, CR1 relay (17, F) is deenergized. The de-energization of the CR1 relay (17, F) causes CR1 switch (18, G) to open, thereby de-energizing the TRl relay (18, F). However, the TR1 switch (22, F) and the TR1 switch (26, G) remain in their closed and opened position for a predetermined time interval after the movement of the LS1 switch from its solid line position to its dotted line position. During this time interval, current flows from L3 through LCS (25, I), thence through FCR3 switch (15, G), thence through FCRZ switch (14, D), thence through FU solenoid (14, C), to L1, thereby maintaining the PU solenoid energized as previously explained. Since the PU solenoid is energized, the FCR1 relay (15, C) is also energized, thereby maintaining the FCRl switch (33, D) closed, whereupon the FFD solenoid (33, B) is energized. Since the CR1 relay (17, G) is de-energized, the CR1 switch (20, E) is closed, and since the FCR3 relay (22, D) is still energized, the FCR3 switch (21, F) is closed. Accordingly, current flows from L3 to L1 through the FFU solenoid (20, C). Referring to Fig. 9, the spool valves and solenoids are in the condition shown by virtue of the previously described condition of the electrical circuit. Therefore, liquid under pressure from the hydraulic pump 88 flows through the line 89 across the spool 86, thence through line 90 across the spool 85, thence through line 92 to the top of the piston within the cylinder 50', forcing the grinding wheel 50 upwardly. The exhaust from the cylinder 50' passes through the line 93, thence through the line 94 to the fine feed selector valve 1416 which has been pre-set for a predetermined rate of feed. Accordingly, the grinding wheel 50 continues to feed upwardly at a fine feed rate after the LS1 switch"(25, G) has been moved to its dotted line position. This fine feed continues during the time interval pre-set on the time delay relay TR1 (18, F) and provides the means for accurate repetitive functions. At the end of the time delay period, the T121 switch (22, F) opens and subsequently, the TR1 switch (26, G) closes. Opening of TR1 switch (22, F) de-energizes the FCR3 relay (22, E), thereby opening and closing the FCR3 switches (15, 14, G), respectively. Closing of the TRI switch (26, G) causes current to flow from L3 through LCS (25, i), thence through the dotted line position of LS1 switch (25, G), thence through TR1 switch (26, G), thence through FCR4 switch (27, G), thence through FCRl switch (27, F), thence through FD solenoid (27, D) to L1. Current also passes through the FCRZ relay (28, D), thereby closing the FCRZ switch (20, F), whereupon the FFU solenoid (20, C) is energized.

Referring to Fig. 12, the solenoids and spool valves are in the position as shown by virtue of the electrical circuit being in the condition just described so that the grinding wheel 50 feeds downwardly at a relatively coarse rate in a manner previously described with respect to Fig. 12. At the bottom of the down feed of the grinding wheel 50, the 103' dog engages the 103' portion of the LS switch (Fig. 12), thereby moving the LS switch (25, GFig. 14) to its solid line position, thereby establishing the circuit for a repetition of the previously described cycle of operations including coarse feed up, fine feed up, and coarse feed down.

Assume that it is desired to pre-set the apparatus to efiect a cycle of operations including coarse feed up, fine feed up, followed by coarse feed down, fine feed down. With the handle 77 (Fig. 16) in the position such that the arrow points to grind on the index, the FF fine feed switch (16, B'Figs. 14 and 16) is moved to the on position, and the fine feed selector switch (17 and 30, CFigs. 14 and 16) is moved to the up and down position. With the apparatus in such condition, and the LS switch (25, G) of Fig. 14 in the solid line position, the spool valves and solenoids will assume the condition as shown in Fig. 11 as previously described, whereupon the grinding wheel 50 will be fed upwardly at a relatively coarse rate until the 103 dog contacts the 103 portion of the LS switch, thereby moving it to its dotted line position. However, since the fine feed selector switches (17 and 30, C) are on the up and down position, the TR1 relay (18, F) will become energized as previously described, whereupon the solenoids and spool valves will assume the condition as shown in Fig. 9, whereupon the grinding wheel 50 continues to feed upwardly at a relatively fine rate of feed throughout the duration of the predetermined time interval set on the time delay relay T R1 (18, F). Upon the completion of this time interval, the TR1 switch (26, G) will close as previously described whereupon the spool valves and solenoids will assume the condition as shown in Fig. 12 whereupon the grinding head 50 will feed downwardly at a relatively rapid rate until the 103 dog contacts the 103' portion of the LS switch (25, G), thereby moving it to its solid line position. However, since the fine feed selector switches (18, 30, C) are in the up and down position, the TR2 relay (31, F) is also energized, causing the solenoids and spool valves to assume the condition shown in Fig. 10, whereupon the grinding wheel 50 continues to feed downwardly at a relatively fine rate throughout the duration of the pre-set time interval on the TRZ relay (31, F). Upon the completion of this time interval, the TR2 switch (23, G) closes, thereby causing the solenoids and spool valves to assume the condition shown in Fig. 11, whereupon the grinding wheel 50 begins to feed upwardly again at a relatively coarse rate and the cycle is repeated until stopped by the operator.

When the operator decides to stop any of the cycles of operation of the grinding wheel 50, he merely turns the handle 77 (Fig. 16) so that the arrow points to the stop position on the index plate. With the apparatus in this condition, the LCS switch (58, F-Fig. 14) closes, and the RC8 switch (58, D) is already closed since the right control station is not being employed and the handle 78 (Fig. 17) must be in the stop position. Accordingly, the CRH? relay (58, A) is energized, thereby opening the CRM switch (49, F) whereupon the TR relay (49, A) is tie-energized. The TR5 relay is a time-delay relay and will be described later. De-energization of the TR5 relay causes opening of the TR5 switch (51, D) whereby the binder solenoid BS (51, A) is de-energized and the spool solenoid (52, A) is de-energized and the spool valve 82 (Fig. 8) is in its upper position as shown. From an inspection of the wiring diagram of Fig. 14, it is also evident that the spool valves 80 and 85 (Fig. 8) are also in their upper positions so that hydraulic fluid under pressure flows from the hydraulic pump 88 (Fig. 8) through the line 89 across the spool valve 86 through line 90 across the spool valves 80 and 85, thence through lines 91 and 94, thence through lines 92 and 93, respectively, so that pressure liquid is directed to both sides of the piston 51 within the cylinder 50' which would normally cause the cylinder 50' and the grinding wheel 50 to move downwardly by virtue of the differential area of the'piston 51. However, pressure liquid flows from the pump 88 through the line 98, thence through line 101 to the binder mechanism including piston 100, thereby causing it to effectively bind the cylinder 50 in fixed position so that no movement of the grinding wheel 50 occurs. Thc reason for using the time-delay relay TR5 (49, A) is to provide a time delay for the opening of TR5 switch (51, D) and the consequent application of the binder to permit the substantially equalized pressure on each side of the piston within the cylinder 50' to slow down the reciprocative movement of the grinding wheel 50 to a substantial stop before applying the binder.

When it is desired manually to control the movement of the grinding wheel 50 in its vertical reciprocation, the handle 77 (Fig. 16) is moved so that the arrow associated therewith is pointing to the manual position on the index plate. With the apparatus in this condition and referring to Fig. 14, LCS switch (57, F) is closed, thereby energizing CR9 relay (56, A). Energization of CR9 relay (56, A) causes closing of the CR9 switch (53, F thereby energizing the PCS solenoid (53, A). Energization of the PCS solenoid (53, A) causes its corresponding spool valve 86 to be in the position as shown in Fig. 7.

Energization of the CR9 relay (56, A) also causes opening of the CR9 switch (49, D) which will effect the de-energization of the TR5 relay (49, A) if the LS switch (50, D) is open. The LS switch (50, D-Fig. 7) is adapted to be closed only when the teeth of the clutch 63 are in engagement. It is designed to prevent the energization of the TR5 relay (49, A) in the event such clutch teeth are disengaged or land tooth on tooth. Should this latter condition occur, it is-necessary that the binder solenoid BS (51, A) become de-energized, whereupon the binder becomes effective to prevent the grinding wheel 50 from decending and causing damage to the work.

Assuming, however, that the teeth do not land tooth on tooth or remain disengaged, and that they completely enmesh, then the LS switch (50, D) closes, whereupon the TR5 relay (49, A) remains energized; consequently, the TR5 switch (51, D) remains closed, and the solenoid BS (51, A) remains energized, thereby effecting dis-engagement of the binder mechanism, and, in which case,

. the corresponding spool valve 83 (Fig. 7) is in its lower valve 83 (Fig. 8) is in the position shown. Energizaticn of the CR10 relay (58, A) also closes the CR10 switch (33, F) whereupon the fine feed down solenoid FFD A33, B) is energized and the spool valve 81 (Fig. 8) is in its lower position. Additionally, the CR10 switch (19, I) is also closed, thereby energizing the FFU solenoid (20, C) and the spool valve 84 (Fig. 8) is also in its lower position. Since the CR10 switch (49, F) is open, not only is the TR5 relay (49, A) de-energized, but the CS position as shown.

Energization of the CR9 relay (56, A) also opens the CR9 switch (52, D), thereby de-energizing the CS solenoid (52, A) and causing its corresponding spool valve 82 to be in its upper position as shown in Fig. 7.

Energization of the CR9 relay (56, A) also closes the CR9 switch (32, F), thereby energizing the FFD solenoid (33, B) and causing the corresponding spool valve 31 to be in its lower position as shown in Fig. 7. Likewise, the CR9 switch (19, I) is closed, causing the energization of the FFU solenoid (20, C) and the corresponding spool valve 84 to be in its lower position as shown in Fig. 7. From an inspection of Fig. 14, it is evident that the PU and FD solenoids (14, C and 27, D) are de-energized, and accordingly, their corresponding spool valves and 85 are in the positions as shown in Fig. 7. Accordingly, fluid under pressure flows from the hydraulic pump 88 to the line 89 and is blocked oil by the position of the '13 spool valve 86. Fluid under pressure, however, passes through the line 98, thence through line 101 to the cylinder containing the piston 100 of the binding mechanism, as well as across the spool valves 82 and 83 through line 9? to the opposite side of the piston 100, thereby dis-engaging the binding mechanism so that the grinding wheel 50 can be moved manually. Oil from the lubricating pump 107, however, at a low pressure in the order of between and pounds per square inch, flows through the line 108, thence across spool valve 36, through line 99, thence across spool valves 80 and 85, through lines 94 and 91, thence through lines 92 and 93 to opposite faces of the piston within the cylinder 50' which maintains the system completely full of oil (at a low pressure) so that when the handle 77 is moved to some other position, such as grind, the apparatus is in condition to immediately function. It is to be noted also that in moving the handle 77 to the manual position, no oil flows through line 102 and the spring 65 (Fig. 6) tends to cause clutch teeth 63 to enmesh. If the teeth 63 land tooth on tooth, of course, the binder is applied as described above. If they enmesh, a certain time element is required to enmesh which permits the grinding head H to slow down due to equal pressure (low) on each side of the piston in cylinder 50. After enmeshing of teeth 63, the head H is held from falling by the nonrotatable sleeve 64 (Fig. 6) which contains the mating teeth for teeth 63.

From the foregoing, it is evident that the apparatus, when in the condition shown in Fig. 7, can be manually operated to reciprocate the grinding wheel 56. This is accomplished by rotating the hand wheel 54 which rotates the splined shaft 57 through the bevel gears 55 and 56. Rotation of the shaft 57 causes manual power to be transmitted through the gear cluster 59, thereby rotating the screw 60, causing its vertical reciprocation since it is threaded to or in threading engagement with the worm wheel 61, as previously described. It is also evident that upon the disengagement of the clutch teeth 63, which is the case during all other conditions of the apparatus for hydraulic reciprocation of the grinding wheel St}, the worm wheel 61 is permitted to idle on its shaft and the screw 60 acts as a rack, rotating such worm wheel as previously described.

During the set-up of the apparatus to perform a desired cycle of operation, it is often necessary to move the head H horizontally at traverse, as well as feed rate in order to position it. As was previously explained in the first part of this specification, the feedworks F is similar to that shown in Patent 2,355,625. One of the exceptions is the manner in which the clutches are actuated and, in the present invention as previously mentioned, they are hydraulically actuated, and the hydraulic fluid therefor is controlled by the action of solenoid valves. Referring to Fig. 14, the TL solenoid (37, A) is energized by closing the traverse left push-button (36 and 38, D), which buttons are located on the leftand right-hand sides of the cross-rail C. Likewise, the TR solenoid (40, A) is energized by closing either of the traverse right pushbuttons (39 and 41, D), which buttons also are located on the leftand right-hand sides of the cross-rail C.

In order to cause horizontal feeding movement of the main head H the FL solenoid (42, A) is energized by closing the feed left push-button switch (42, D), which is located on the right side of the cross-rail C, while rightward feeding movement of the main head H is effected by energizing the solenoid FR (44, A) by closing the feed right push-button switch (44, D), which is also located on the right-hand side of the cross-rail C. On the lefthand side of the cross-rail, an On-Off switch (43, B) is provided for shunting out the push-button switches (42 and 44, D) for efiecting the feed left and the feed right of the main grinding head H The previously described 14 push-buttons for feed left and feed right provide means for manually feeding the head H independently of the manual position on the index plates of Figs. 16 and 17.

From an inspection of the wiring diagram (Fig. 14), it is evident that the time-delay relays TR1 and TRZ (18 and 31, F) can be used to serve a dual function. They can be used to provide a period within which fine feed and dwell is occasioned, as previously described. They also may be used to operate the feed solenoids FL or FR (42 and 44, A) of the feedworks for a pre-determined time to thereby provide an in feed of the head H toward the work. This can be done by simply providing a selector switch in conjunction with the time-delay relays for rendering said time-delay relays effective for fine feed and dwell or for feedworks operation.

During set-up it is also often desirable to manually control the hydraulic actuation of the grinding wheel 50 in both an upward and downward movement. Referring to Fig. 16, movement of the handle 77 so that the arrow points toward the down index on the index plate causes closing of LCS switch (26, I), thereby energizing the feed down solenoid (27, D), provided that the On-01f switches (12 and 14, J) are in the solid line positions. This latter condition occurs when the fine feed switches (17, A and B) are in their OE positions. Additionally, energization of the solenoid FD (27, D) energizes FCR2 relay (28, D), thereby closing FCRZ switch (20, F), whereupon the FFU solenoid (20, C) is energized. With these two solenoids energized, the apparatus is in a condition as shown in Fig. 12 and the grinding wheel 50 .continues to move downwardly until the handle 77 (Fig. 16) is moved such that the arrow is moved off the Down index. Should the handle 77 not be moved, the grinding wheel 59 continues downwardly until the positive stop 109 is engaged, whereupon further downward movement of the grinding wheel 50 ceases.

Referring to Fig. 16, movement of the handle 77 so that the arrow points toward the up index, causes LCS switch (14, I) to close, whereupon the PU solenoid (14, C) and the FCR1 relay (15, C) are energized, thereby effecting upward movement of the grinding wheel 50 for such time as the handle 77 remains in the position it was placed, or until the positive stop 110 is engaged.

Referring to Fig. 7, liquid under pressure flowing through line 98 also flows through line 111 to a manually-operated reversing valve 112 which controls the flow of the pressure liquid to alternate sides of a piston within a cylinder, 113. The piston within the cylinder 113 is connected to a dressing diamond 114 (Fig. 1) that is adapted to dress the grinding wheel 59 when the same has worn due to working operations.

It is often desirable during set-up to jog the rotation of the work-supporting table W. Referring to Fig. 13, this can be effected by closing the push-buttons 116 and 117 (see also Figs. 16 and 17) which energizes M relay (108, J) for as long as the push-buttons 116 and 117 are depressed.

The side head H is provided with an electrical circuit substantially identical with that shown in Fig. 14, which electrical circuit is shown in Fig. 15. Inasmuch as the operation of the grinding wheel is substantially identical with the movement of the grinding wheel 50 of the main head H it is believed unnecessary to specifically describe the electrical circuit since an understanding of the circuit for the main head H should suffice.

Although the various features of the improved grinding machine have been shown and described in detail to fully disclose one embodiment of the invention, it will be evident that numerous changes can be made in such details, and certain features can be used without others without departing from the principles of the invention.

What is claimed is:

1. A grinding machine comprising in combination, a base; a work-supporting table mounted on said base; a

vertical standard attached to said base; a cross-rail mounted on said standard; a saddle mounted on said cross-rail and adapted to be moved to various positions horizontally along said cross-rail; a reciprocable hydraulically-actuated main grinding head having a grinding wheel, mounted on said saddle; a reciprocable hydraulically-actuated side grinding head having a grinding wheel mounted on said vertical standard and adapted to be moved to different vertical positions therealong; electrically-operated valves for controlling the flow of liquid to said heads; an electrical circuit for said electricallyoperated valves including means for operating certain of said valves to exhaust the liquid from said grinding heads at a relatively rapid, and at a relatively slow rate for a predetermined time interval; and a plurality of control stations located at convenient points relatively to said grinding machine and embodying pre-settable control members for said electrical circuit, whereby said grinding heads can be caused to produce different cycles of operations.

2. A grinding machine comprising in combination, a base; a work-supporting table mounted on said base; a vertical standard attached to said base; a cross-rail mounted on said standard; a saddle mounted on said crossrail and adapted to be moved to various positions horizontally along said cross-rail; a reciprocable hydraulicallyactuated main grinding head having a grinding wheel mounted on said saddle; a reciprocable hydraulicallyactuated side grinding head having a grinding wheel mounted on said vertical standard and adapted to be moved to different vertical positions therealong; electrically-operated valves for controlling the flow of liquid to said heads; an electrical circuit for said electricallyoperated valves, including means for operating certain of said valves to exhaust the liquid from said grinding heads at a relatively rapid, and at a relatively slow rate for a predetermined time interval; a plurality of control stations conveniently located relatively to said grinding machine for the operator thereof, and including control means thereon for pre-setting said electrical circuit for causing said grinding heads to produce pre-determined cycles of operation; and electrically-operated positive interlocking means for rendering one of said control stations inefiective when the other is effective.

3. A grinding machine comprising in combination, a base; a rotatable work-supporting table mounted on said base and including a magnetic chuck; a vertical standard associated with said base; a cross-rail mounted on said vertical standard; a saddle mounted on said cross-rail for movement horizontally therealong; a feedworks transmission for efliecting the horizontal movement of said saddle; a grinding head pivotally mounted on said saddle; a side grinding head mounted on said standard and adapted to be moved to difiierent vertical positions therealong; a feedworks transmission adapted to elfect the vertical movement of said side grinding head; hydraulic means for reciprocating each of said grinding heads; electrically operated valve means for controlling said hydraulic means, a head stock transmission for rotating said work-supporting table; an electrical circuit for controlling said electrically-operated value means and adapted to be pre-set for causing said grinding heads to produce predetermined cycles of operation, and including means for preventing the rotation of said Work-supporting table until said magnetic chuck has been energized; and a plurality of control stations in convenient positions relatively to said grinding machine including interlocked, pre-settable control means for said electrical circuit.

4. A grinding machine comprising in combination, a base; a work-supporting table mounted on said base; a vertical standard attached to said base; a cross-rail mounted on said standard; a saddle mounted on said crossrail and adapted to be moved to various positions horizontally along said cross-rail; a hydraulically-actuated main grinding head mounted on said saddle; a hydraulically-actuated side grinding head mounted on said vertical standard and adapted to be moved to different verticalpositions therealong; electrically-operated valves for controlling the flow of liquid to said heads; an electrical circuit for said electrically-operated valves, including means for operating certain of said valves to exhaust the liquid from said grinding heads at a relatively rapid, and at a relatively slow rate for a predetermined time interval; and a control station located at a convenient point relatively to said grinding machine and embodying pre-settable control members for said electrical circuit, whereby said grinding heads can be caused to produce dilferent cycles of operations.

5. A grinding machine comprising in combination, a base; a work-supporting table mounted on said base; a vertical standard attached to said base; a cross-rail mounted on said standard; a saddle mounted on said crossrail and adapted to be moved to various positions horizontally along said cross-rail; a hydraulically-actuated main grinding head mounted on said saddle; a hydraulically-actuated side grinding head mounted on said vertical standard and adapted to be moved to different vertical positions therealong; electrically-operated valves for controlling the flow of liquid to said heads; an electrical circuit for said electrically-operated valves; and a control station conveniently located relatively to said grinding machine for the operator thereof, and including control means thereon for pre-setting said electrical circuit for causing said grinding heads to produce predetermined cycles of operations.

6. In a grinding machine comprising an hydraulicallyreciprocable grinding head; electrically-operated valves for controlling the flow of liquid to and from said grinding head; an electrical circuit for controlling the actuation of said valves, including means for exhausting the liquid from said grinding head at a relatively rapid rate; means within said electrical circuit for exhausting the liquid from said grinding head at a relatvely slow rate; a positive stop against which said grinding head is adapted to be moved while said liquid is being exhausted at said relatively slow rate and a time-delay solenoid in said circuit for causing the continued exhausting of the liquid from said grinding head at said slow rate for a pre-set time interval after said grinding head has moved against said positive stop.

7. In a grinding machine including an hydraulically-reciprocable grinding head; electrically-controlled valve actuating mechanisms for controlling the flow of liquid to and from said grinding head; means for supplying said liquid to said grinding head under substantially a constant pressure; an electrical circuit for controlling said valve actuating means including means for exhausting liquid from said grinding head at a relatively rapid rate for a predetermined portion of either of its reciprocative strokes; means for exhausting the liquid from said grinding head at a relatively slow rate during a predetermined portion of the reciprocative strokes of said grinding head; adjustable positive stop means at each end of the reciprocative stroke of said grinding head adapted positively to stop the motion of said grinding head when said liquid is being exhausted therefrom at said relatively slow rate and time-delay solenoid means in said circuit for causing the continued exhausting of the liquid from said grinding head at said slow rate for a pre-set time interval after said grinding head has moved against said positive stop means.

8. In a grinding machine including an hydraulicallyreciprocable grinding head; electrically-controlled valve actuating means for controlling the flow of liquid to and from said grinding head; an electrical circuit for controlling said valve actuating mechanism; a limit switch within said electrical circuit adapted to be actuated near the end of each reciprocative stroke of said grinding head; a time-delay relay within said electrical circuit adapted to be actuated by said limit switch for operating said valve 

